This invention relates generally to improvements in medication infusion devices for use in delivering a selected medication to a patient. More specifically, this invention relates to a medication infusion device such as a programmable infusion pump or similar apparatus adapted for response to a parameter indicative of patient condition, such as a current blood glucose reading.
Infusion pump devices and systems are generally known in the medical arts, for use in delivering or dispensing a prescribed medication to a patient. In one form, such devices comprise a relatively compact pump housing adapted to receive a syringe carrying a prescribed medication such as insulin for administration to a patient through infusion tubing and an associated catheter or the like. The infusion pump operates a small drive motor connected to a syringe piston plunger to administer the medication to the patient.
Programmable control means are normally provided for operating the pump drive motor continuously, or at periodic intervals, to obtain a closely controlled and accurate delivery of medication over an extended time period. Such infusion pumps are utilized to administer insulin and other medications, with an exemplary pump construction being shown and described in U.S. Pat. Nos. 4,562,751; 4,678,408; and 4,685,903.
A typical programmable infusion pump includes a plurality of externally accessible control switches or buttons which can be manipulated in relation to a visual display to program the pump in accordance with patient medication requirements. Initial pump programming is normally performed by the patient's physician or by other medical personnel. However, particularly in the case of infusion pumps used to administer insulin to diabetic patients, the control buttons and related pump control circuitry are often designed to accommodate at least some patient intervention to vary medication delivery times and doses in accordance with anticipated patient requirements.
One alternative medication infusion device comprises a compact syringe-type implement constructed to resemble a fountain pen or the like, and thus adapted to be carried easily and conveniently by the patient. See, for example, U.S. Pat. Nos. 5,383,865 and 5,391,157, and European Patent Publication 0,554,995. Such pen-like implements include a rotatable dial or knob for retracting a syringe plunger through a predetermined stroke, with a visual display providing an indication of the medication units or volume to be delivered upon subsequent manual advancement of the plunger. The patient can thus set the implement to deliver a desired dosage, and then press the plunger to deliver the medication. The medication dosage and frequency are, of course, developed according to a dispensing protocol to meet the needs of each specific patient.
In recent years, there has been considerable interest in the development of improved medication infusion devices which can be used to deliver medication to the patient in accordance with current or actual patient requirements, as distinguished from anticipated medication requirements. In this regard, blood chemistry readings can provide current information regarding important patient condition parameters that can affect current or actual patient medication requirements. For example, blood glucose readings represent key data that can be used to determine current insulin requirements of a diabetic patient. Extensive research is ongoing with respect to the development of improved and reliable glucose sensors, for example, as described in U.S. Pat. Nos. 4,650,547; 4,671,288; 4,781,798; 4,703,756; and 4,890,620. Similarly, a variety of systems have been proposed for use of a glucose sensor to automatically alter the operation of a medication infusion pump in response to current patient requirements, as described, for example, in U.S. Pat. Nos. 4,633,878; 3,837,339; 5,101,814; and 5,372,133.
While automatic control of an infusion device for insulin or other medication appears to be a desirable approach for some patients, diabetic patients often need more flexibility in their individual medication delivery protocols in order to accommodate a normal daily living schedule. That is, while a current blood glucose reading is an important factor in determining medication requirements, variable daily activity such as changing eating schedules, exercising schedules, etc., should be taken into account in determining the actual dosage and timing of medication delivery to each individual patient.
There exists, therefore, a significant need for further improvements in medication infusion devices of the type adapted for response to a current patient condition parameter, such as a current blood glucose reading, wherein actual dispensing of medication to the patient represents a balanced response which considers the monitored parameter in addition to current subjective patient activity factors. The present invention fulfills these needs and provides further related advantages.